This invention relates to pumping cams and methods for injecting fuel into the combustion chambers of internal combustion engines. In one aspect, this invention is directed to a new and improved cam which is sinuously profiled with arcuately spaced compound cam pumping stations to produce pulse waves of controlled quantities of fuel with a fast initial rate and a subsequent soft end of injection for improved burns having reduced particulate emission for low engine loads, and further, with a fast initial rate and a fast end of injection with increased fuel supply for engine starting and high horse power demands. Another aspect of this invention is directed to a new and improved method of fuel injection with a compound cam that shapes the profiles of pulses delivered to the engine combustion chambers.
Fuel distributor pumps have employed circular cams to inject pulses of fuel into the combustion chambers of internal combustion engines. In diesel engine application in which ignition results from high compression of the air-fuel mixture, the shape (profile and quantity) of the pulse waves of fuel injected into the combustion chambers is of great importance for improved burns over a wide range of engine loads. By varying the rate of injection for various engine loads, it is possible to obtain improved fuel economy with reduction in noise, particulate emissions and Nox.